In recent years, vehicle devices having a function of downloading data from an external server have been known. For example, Patent Literature 1 discloses the function of downloading update data for the vehicle device. The recent vehicle device can execute not only a native application preliminarily installed in the vehicle device, but also an external application downloaded from an external device such as the server. In that case, the downloaded external application and data used by the external application are written into a storage unit.
However, since the external application is downloaded by a user, it is difficult to predict application type and download size of the external application, and rewriting frequency of the storage unit by the downloaded external application. When the rewriting in the storage unit is performed beyond a durability of the storage unit, a reduction in performance of the storage unit such that failure of data storing may be occurred.